KR810000747B1 - Method of preparing particle board that has phenol form aldehyde resin barrier on its surface - Google Patents

Abstract

A method of making an overlayed product with comminuted cellulosic material as the core thereof comprising;producing a furnish of the comminated cellulosic material by mixing with an organic polyisocyanate which operates upon the application of heat and pressure to bond the material; preparing a sheet overlay with phenol formaldehyde resin distributed in said overlay toward said mat; and said overlay to form an integral product by the application of heat and pressure, the phenol-formaldehyde resin dring such consolidation forming a resinous barrier inhibiting penetration of the polyisocyanate through the overlay.

Description

Manufacturing method of surface layer product

The present invention relates generally to the manufacture of a plate-like product having a surface layer by combining a core part of a cellulose-based material in powder or particulate form with a coating part bonded thereto.

Many structural products are manufactured by a basic process of joining a cellulosic body using pressure, heat and a compounding binder. These structural products include plywood, cardboard, particle board, and veneer surface particle boards, as well as vegetable fibers such as corn stalks, straw and bagasse, pulp, and waste paper. Squeezed or framed products of other cellulosic materials, such as). Adhesives or binders typically used to make these products include phenol-formaldehyde, resorcinol-formaldehyde, melamine-formaldehyde, urea-formaldehyde, and furfuran alcohol resin condensed with urea-furfural. Thermosetting water is used.

In recent years it has been noted to use polyisocyanates as binders to prepare the conjugated products.

In most cases polyisocyanates are in liquid form but can sometimes be dry powdery. The polyisocyanate is mixed with the cellulosic material to form a joint feed to apply heat and pressure to bond to cause the powdery material to become a solid.

The products produced in this way show good strength and weather resistance, but unfortunately the adhesion of isocyanates to metals causes serious problems due to this adhesion in typical press processes in panel manufacturing.

For example, considering the production of veneer surface particleboard, when polyisocyanate is used as the binder, polycyanate tends to penetrate or penetrate into the veneer during the press process, causing adhesion with the retinal plate used in the press and thus a special separation agent. Without iii), the product will stick to the retina plate during the press process.

The present invention relates to the production of bonded products, which essentially eliminates the sticking that normally occurs when using polyisocyanates and further provides the opportunity to manufacture very good mold boards with exceptionally good strength and durability and durability against stormy weather. Thus, a feature of the present invention is a new process for preparing conjugated products from powdered cellulosic materials, which allows the use of phenol-formaldehyde resins to secure a surface layer for the core of the bonded cellulosic material compared to polyisocyanates.

The present method achieves good conjugation between the surface layer and the core, which is believed to be due to some reaction between the isocyanate groups and the free hydroxyl groups in the phenolic resin in the junction feed. In addition, phenol-formaldehyde resins are effective in forming a barrier that prevents condensation reactions during the press process and prevents the polyisocyanate of the feed from permeating the surface layer and contacting the retina plate used in the press. The use of polyisocyanates as binders for core cellulosic materials minimizes the production of vapors, which is a common experience when the joints are produced, where steam builds up in the core, causing removal problems. The deflection of the core, that is, the tendency of the core to expand following the press process, becomes less important. By setting the conditions, the post-polymerization reaction, that is, the polymerization of the binder in the core part of the press process, is less important than the polymerization reaction in the joint feed containing the phenolic resin binder which causes the exothermic reaction.

The present invention is particularly suitable for the production of bonding products having a surface layer made of a thin plate, ie, a paper plate, etc., which can pass water of the surface layer. In this connection it is somewhat surprising that paper has been known to wet the paper prior to introducing the bonding feed and the paper surface structure into the press when paper is used. As a result of this wetting, the polymerization reaction of the phenol-formaldehyde resin, which bonds the surface layer to the core portion, is certainly delayed to a sufficient degree so that the pressure of the press can make an optimum contact between the cellulosic material of the bonding feed and the paper. The heat of the press converts the water in the paper into steam and eventually bleeds it out of the paper, which has the effect of slightly plasticizing the cellulosic material of the bonding feed. A very good product, which is excellent for use in exterior applications, is produced and at the same time excellent in eliminating sticking to the retinal board has been achieved.

The present invention has the advantage of using other types of surface layers, such as veneer surfaces. It can be carried out using various types of phenol-formaldehyde resin deposition layers as binders for the surface layer, including so-called adhesive valves, resin valves, and the like, which contain a resin held on a cellulose mediator. Therefore, a general goal is to provide an improved process for producing bonding products from powdered cellulosic materials containing polyisocyanates as binders for the core. Another purpose is to prepare a new product by this process. A further refined goal is to provide a new method for the production of conjugated products characterized by the use of phenol-formaldehyde resins to bond veneers or other surface layers to the core wood during operations during heat and pressure bonding the granules. It is. In particular, it is to prepare a new process for preparing a bonding product using a water-permeable surface layer, such as a paper valve, which is completely saturated with water, before being introduced into the press process. These objects and advantages are achieved by the present invention and are described below in connection with several specific examples that illustrate the present invention in detail.

In practicing the present invention, a binder system is employed to prepare a cellulosic junction feed containing polyisocyanates and formaldehyde. Such binders, for example, can be used to produce products with good strength and moisture resistance, eliminating the need to pre-dry the cellulosic material with a cellulose starting material with a fairly high moisture content, i.e. a moisture content of up to 22%. It has been known that it can be used to prepare a junction feed.

The polyisocyanate component of the binder system is suitable if it is any polyisocyanate containing at least two active isocyanate groups per molecule or a mixture of these compounds. Examples of the polyisocyanate which can be used include diphenylmethane diisocyanate, m- and P-phenylene diisocyanate, phenylene diisocyanate, toluene diisocyanate, toluene triisocyanate, triphenylmethane triisocyanate and diphenyl ether-2,4,4 '-Triisocyanate is included. Particularly suitable are polyphenylisocyanates such as diphenylmethane-4,4'-diisocyanate. Mixtures of polyisocyanates can also be used, such as polymethylenepolyphenylisocyanates having three groups, such as PAPI (manufactured by Upjohn Company).

At room temperature, formaldehyde is a gas. Therefore, a suitable concentration of water-soluble formaldehyde solution is used in the binder system, for example 37%, 44%, etc., which are commercially available. The ratio of isocyanate to formaldehyde is not very important when using polyisocyanate and formaldehyde in preparing the junction feed. The optimum ratio of a given application is usually determined under normal experiments. Polyisocyanate; The ratio of formaldehyde in the range of 2: 3 to 5: 1 was successfully performed. The ratio between 1: 1 and 4: 1 is used to obtain the odor treatment and economics that are usually generated. Likewise, the amount of binder required for a particular application is usually determined by simple experiments. A quantity ranging from 2 to 5% based on the dry weight of the cellulosic material has given good results. The weight and percentages are discussed here in terms of solid components, except where noted. Cellulosic subgrades used to make the joint feed, which are the core of the joint product of the present invention, include particles of material, in particular large rice in planers, wood particles from wood product waste, veneer chips and the like. Mixtures of cellulosic particles are also used if desired. Thus, a joint feed has been prepared from a mixture of wood particles containing up to about 30% of the bark. Other materials include particles from cornstalks, straw, waste paper, and the like. The production of particleboard type products and the use of binder systems comprising formaldehyde and polyisocyanates allow the moisture content of the particles to be up to 22% by weight. Typically particles made from wood chips material contain about 10-20% moisture and are used without first drying. To achieve maximum economics in drying operations, ordinary particles are often used with moisture content of about 6% or more. However, particles containing less moisture can also be used, but these unnecessary additions are added to the price of the dryer.

The conjugation feed can be prepared using polyisocyanates of the type described above as a binder without formaldehyde.

In preparing the junction feed from the powdered cellulosic material, the binder used may be sprayed onto the surface while rotating or shaking in the mixer. If polyisocyanate and formaldehyde are used as the binder, they can be added separately or in order of importance.

Moreover, even when waxes, sizing materials, flame retardants and the like are used in the joint feed, these are of course usually mixed with the powdered material together with the binder. As contemplated by the present invention, in preparing a bonding product such as a particle board in which a surface layer is bonded with veneer, paper, etc., the surface layer diffuses therein, and the bonding product forms the core at the end. It is shown in the surface layer of the mat layer of the bonding feed. During the press process, the phenol-formaldehyde resin is cured to bond the polyisocyanate to the cellulosic material in the core to make it weatherproof. The resin also creates a barrier that prevents polyisocyanates from penetrating the surface layer. Therefore, even thinner veneers or even paper can be used as the surface layer without isocyanate sticking to the retina plate in the press. Furthermore, the final bond between the core and the surface layer in the conjugate product is excellent and is thought to be at least partly due to chemical reactions taking place on the isocyanate binder and the phenol-formalin resin.

Usually, the resin in the surface layer is distributed at a ratio of 11 to 86 gms / m 2 as a solid basis and is bound to the core. In the bonding of the cellulosic material used and the polyisocyanate binder together, the isocyanate group of the polyisocyanate is combined with the free hydroxyl group of the cellulosic material to form a urethane bond for the reason of forming a urethane bond. It seems to be.

This reaction is illustrated by the following scheme where C ₁ and C ₂ represent adjacent bodies of cellulose material and R represents the nonisocyanate portion of the polyisocyanate molecule.

In addition, some of the polyisocyanates react with water in the form of moisture in the feed to form a polyurea by the following scheme, where R ₁ , R ₂ represent the nonisocyanate portion of the other polyisocyanate molecules. If formaldehyde is present, the polyurea produced by this method reacts with formaldehyde to form a polyurea-formaldehyde resin, which helps the cellulosic bodies to contact together.

The phenol formaldehyde resin in the surface layer allows the surface layer in the bonding product to bond with the core, which in turn contains phenolic hydroxyl groups that can be combined with the isocyanates present in the polycyanate to form urethane bonds according to the first reaction mentioned above. do. Thus, the resins in the surface layer, like the chemical bonds mentioned above, form normal adhesive bonds with the core, while still playing an important role as a barrier to preventing polyisocyanates from contacting the retinal plates that penetrate the surface layer to produce the bonding product. I think you are doing.

The present invention has particular utility in the manufacture of bonding products having a surface layer comprising a paper valve bonded to the core. Paper is a material that is fairly permeable and usually uses paper valves, which shows many difficulties in producing products using isocyanate binder systems for granules. By including phenol-formaldehyde in the surface layer, very good products can usually be produced without the expected sticking.

The use of isocyanate binders for the cellulosic material in the core can minimize the formation of steam in the core to minimize the swelling problem that is exacerbated by the presence of the surface layer during the press process. Polyisocyanate bonded to the core shows minimal bending, ie, increase of the core after the end of the press process.

For example, a bend of 0.013 cm or less is commonly known at a core of 1.59 cm thickness.

It is known that very good results are obtained when the paper of the surface layer is saturated or submerged with water before bonding under pressure and heat in the production of the bonding product of the paper surface layer. This can be done by spraying water onto the paper or coating with a roller on the face of the opposite mat paperboard during the preparation of the assembly passed through the press. The amount of water introduced is usually in the dry weight range of about 75 to 200% of the paper weight.

This immersion of the surface layer during this press and generation of vapors in the submerged valve area ensures sufficient pressure to apply the polymerisation of the phenol-formaldehyde resin until the particulate material at the core is very close.

Certainly moisture or the generated vapors also help to significantly plasticize the cellulosic material, which apparently allows the polyisocyanate in the conjugate feed to more fully bind with the cellulosic material. Whatever the phenomena involved, it can be produced to withstand the most extreme cases of normal testing applied to joint products for evaluation in exterior use.

In practical application of the present invention, the press temperature is typically in the range of 135 ° to 220 ° C. The following will be examples illustrating the present invention in detail.

Example 1

Particleboard boards with paper surface were made as follows. Tree trunks, boughs and bark were passed through a chipper through a small piece of green grassy pine, including needle-shaped leaves, to be crushed through a 0.653 cm diamond screen. Filling consisting of 2500 gm of final powder, containing about 15% by weight, was sprayed separately with 37% formaldehyde solution and about 64 g PAPI while mixing 23 g in a drum mixer to introduce surface aldehyde. The resulting joint feed thus contained about 18.2% moisture by weight. This junction feed had a 0.0025 cm phenol-formaldehyde resin bond line applied on one side (weight of adhesive line about 40.5 gm / cm 2) and treated with this phenol-formaldehyde resin produced by a beater loading process. 6.35 cm thick on the surface with a surface layer of paper plate treated with this phenol-formaldehyde resin prepared by fixation, 0.046 cm thick plate Crezon B210 produced by Crown Zellerbach Corporation. Of the metrocer planet. The met provided a line of crease for the Crezon valve facing away from the mat. Another crease valve was prepared. Another Crezon valve was placed on top of the mat and the resulting sandwich was compressed to 5 minutes at a pressure of about 22.1 kg / cm 2, about 190 ° C., about 1.22 cm thick. The resulting paper-board particleboard nucleus triangular plates had an average density of 697 kg / m 3, an average burst coefficient (MOR) of 137.37 kg / m and an average modulus of elasticity of 24.798 kg / cm 2 when tested using the ASTM process.

Example 2

The amount of powder of recently dead Lodgepole pines produced by the method mentioned in Example 1 was introduced by weight ratio 1.5% pApI and powder by 0.5% formaldehyde (37% formaldehyde) based on the dry weight of the tree. The joint feed was prepared by mixing with the same material.

The surface layer of the plate is 0.254 cm thick Western Larch veneers on the surface of solid phenol-formaldehyde resin (48% solid liquid resin, product number OPA-197A at the rate of 21.5 gm / m2 solid base). The Coos Bay Division of (Georgia Pacific Corporation) prepared the spray by spraying the granules bonded to the opposite side by the adhesive line of the surface facing the mat and veneer surface. The mat was made from the feed, and when compressed as in Example 1, the granules produced a final plate having a thickness of about 1.9 cm and an average density of about 640 kg / m3. The bursting coefficient was about 464 kg / cm 2 and the average elastic modulus was about 69.250 kg / cm 2.

Example 3

Particleboard products of veneered cotton were prepared from the Ponderosa pine planer batter and prepared from the bonding feed. To prepare the junction feed, a 2 kg weight pad was hammered to pass through a 0.635 cm diamond screen and placed in a mixer containing 11.6% moisture by weight.

While in the mixing vessel, Great Fat Bob was sprayed with 37% aqueous formaldehyde solution and about 53.1 gm to introduce 47.8 gm formaldehyde. About 35.4 gm microcrystalline emulsions containing 50% by weight wax solids by weight were also added to reduce moisture absorption in the final product. Suitable emulsions here are commercially available as Paracol 915N 의 from Hercules, Inc.

The resulting bond product was about 7.6 cm thick on a 0.254 cm Douglas fir veneer coated with a solid base phenol formaldehyde resin (OPL-197A) 21.5 gm / m2 pre-sprayed to form an adhesive layer in the surface layer disposed between the mad and plate. It was formed to form. Similar Douglas fir veneers were sprayed with resin and placed on top of the mat with a bonding layer facing down the mat.

The resulting creep was compressed to about 191 ° C. at a maximum pressure of 22.14 kg / cm 2 for about 5 minutes to 1.27 cm thick.

According to the ASTM test method, the plate had an average burst coefficient of about 773 kg / cm 2 and an average modulus of elasticity of about 91.400 kg / cm 2.

Example 4

In another recipe, 2.2 kg of Ponderosa pine planer fat balm containing 10% moisture by weight is placed in a mixer where the fat rice is a polymethylene polyphenylisocyanate having almost three functional groups to prepare the junction feed. 99 gm of liquid and Paracal 915N were mixed.

The surface layer was prepared by applying an adhesive line to such a veneer surface coated at a ratio of 54 gm / m 2 of resin from a 0.254 cm thick lachi veneer. The resin used was a phenol-formaldehyde resin obtained from Bordens (MH-193-92; viscosity 300 ± 50 CPS ⓐ 25 ° C .; pHz 10.3, specific gravity 1.22 ⓐ 21 ° C.) sprayed with 40% solids.

The mat provided a 6.35 cm thick joint feed on the sprayed surface of one surface layer. This was previously compressed to 0.049 kg / cm 2 in a cooling press, and the other surface layer was placed on top with the resin sprayed side down. The resulting granules were then placed in a heating press and compressed at 177 ° C. for 5 minutes.

The maximum pressure used was 21.1 kg / cm 2 and the press was close to making the desired thickness. The 1.25cm thick plate had an average density of 644kg / ㎥, an average burst coefficient of 794kg / ㎠, and an average elastic modulus of 85.634kg / ㎠.

Example 5

In another preparation, the surface layered particle board product was prepared from the junction feed prepared as mentioned in Example 4. The surface layer is a reichhold chemical with plyocite plate high density phenol-formaldehyde on the retinal plate [paper plate film high density surface layer 0.023mm thickness, 181gm / m 2 weight and 50% resin content] American product standard for construction and industrial plywood manufactured by a chemical company PS-1-74] was prepared by placing a plyophen plate on a veneered sheet with a 0.254 cm thick lachi veneer. Pliophen is a continuous dry film of retained phenolic surface aldehyde resins of cellulosic media produced by Reichholdh Chemicals Co., Ltd., paper with 0.098mm thickness, 67.14kg / m2 weight and 65% resin solids. It is a bond line product. The mat was then made from a 4.44 cm thick joint feed on the prepared surface layer. The mat and underlying surface layer were pre-compressed at 0.049 kg / cm 2. The other surface layer was placed on a precompressed assembly similar to the surface layer mentioned above and these were placed on the mat with paper adhesive lines placed opposite the mat. Another retinal plate was placed on top of the assembly and the assembly was placed in a heating press with the applied pressure for 5 minutes at 177 ° C., 22.5 kg / cm 2 maximum pressure.

The plate was 1.217cm thick, 663kg / m 3 density, rupture coefficient 1332kg / cm 2 and elastic modulus 161,340kg / cm 2. The invention used as mentioned above can produce an excellent form of the surfaced product, where the surface layer contains a material that can submerge water, such as paper, and such is submerged in water before applying heat and pressure.

The following example illustrates this form in manufacturing.

Example 6

The surfaced paricleboard product was prepared using the junction feed of Example 4. Kraft paper (127 gm / m 2) was sprayed onto this side having the application rate of 53.8 gm / m 2 resin (solid base) of the phenol-formaldehyde resin of Example 4 to provide a phenol-formaldehyde resin adhesive layer on one side. The other side of the plate was sprayed with water to hold about 172 gm / m 2 of paper plate. The wet paper plate was placed on the retinal plate with the resin coated side facing upwards.

The mat provided such a plate about 3.81 cm thick and the mat and underlying surface layer were pre-compressed at 0.049 kg / cm 2. Another surface layer was prepared on this precompressed assembly with the coated side of the wet plate facing down on the mat. Another retinal plate was placed at the top of the upper surface layer. The entire assembly was then placed in a press where they were pressed for 3 minutes at 177 ° C. and a maximum pressure of 21.1 kg / cm 2.

The plate was made to have a thickness of 0.734 cm, a density of 717 kg / m 3, a rupture coefficient of 224 kg / cm 2, and an elastic modulus of 31,970 kg / cm 2. It did not flex after boiling for 4 hours.

Example 7

The plates described above can be further processed to produce products with veneer faces. Thus, as in Example 4, a 0.254 cm Larch veneer plate sprayed with resin was prepared, and the adhesive layer was dried for 2 hours by applying air. Polymethylene polyphenylisocyanate liquid was applied to the opposite side of the paper layered product using an application rate of 43.06 gm / m 2. Thereafter, a paper coated product treated with isocyanate was prepared between the lachivenia plates with the resin coated faceplates facing inwardly opposite the paper coated plates. This granulated body was placed between the retinal plates and pressed for about 3 minutes at 177 ° C and a maximum pressure of 12.3 kg / cm 2. There was a plate product with very good veneered surface, which did not show curvature even after boiling for 4 hours. The prepared plate was 1.217 cm thick, 687 kg / m 3 density, burst coefficient 1.010 kg / cm 2 and modulus of elasticity 116.862 kg / cm 2.

In all of the above described examples no mention is made of sticking on the retinal plate due to polyisocyanates. As a result, there is no need to introduce a separating agent that prevents sticking by such isocyanates.

Claims (1)

As described in the text, a powdered cellulose material is mixed with an organic polyisocyanate to apply heat and pressure to combine the materials to form a bonded feed to form a mat from the adjoining feed to one side of the mat. In the method for preparing the granules forming the surface layer of the mesh tube, the phenol-formaldehyde resin is distributed in the electrical surface layer, and the resin-coated side layer is directed toward the mat, applying heat and pressure to the mating feed in the aforementioned mat and A method of forming the aggregated product by bonding the surface layer, in which the phenol-formaldehyde resin forms a resinous barrier that prevents polyisocyanate from passing through the surface layer. A method for preparing a plate product having a surface layer from an acidic substance.